The present invention generally relates to a picture image color separating apparatus to be used when block copies for dyeing use are made in a dyeing business.
Conventionally the following three processes are mainly required when block copies for dyeing use are made in accordance with the illustration with the use of microprocessors and so on.
(A) Illustrations are loaded in a picture image input portion such as scanner or the like and are converted into picture image data, which are more in the color number of 32 gradations about each of R (red), G (green), B (blue).
(B) Picture image data obtained by the (A) are separated into the color number of the sheets of the block copies considered property. Hereinafter such an operation is called color separation.
(C) The picture image data separated in color in such a manner as described hereinabove are outputted in block copy for each color.
The above described processes will be illustrated by way of a case where the block copies for dyeing use are made from the illustration in FIG. 2.
An illustration in FIG. 2 loaded by a scanner is converted into a picture image data of many gradations. Further, the picture image is converted into a color separating picture image with a representative color as shown in FIG. 3 by the color separation. The picture image separated into the representative colors are outputted for each of the representative colors, and such block copies as shown in FIG. 5 are outputted in accordance with the color separation picture image data.
Here the color separation of the above described (B) may be further separated into the following two processes. Namely,
(B-1) Color representation is optionally selected and is determined (hereinafter referred to as color specification.)
(B-2) A picture image is separated by a representative color determined by the above description (B-1).
Such three methods as shown hereinafter are provided when the process of the above description (B-1) is embodied.
(B-1-1) Representative colors are to become particular colors (black, white, blue, red, green and so on) in spite of the color characteristics of the original picture image.
(B-1-2) The color of the original picture image is sampled so as to compose an area histogram for each color. A representative color is determined by the cluster analyzing with color difference (interval in color space) and area as evaluation elements.
(B-1-3) An operator selects a proper color with a sensory judgment so as to determine representative colors.
It is easily judged that the color error between the original picture and the color separation picture image is less in the color separation through a representative color guided by the color distribution of the picture image through the (B-1-2), instead of the color separation through the representative color fixed by the above described (B-1-1). It is possible to produce color separation picture images which are extremely reduced sensuously if an operator of the (B-1-3) optionally determines the representative color, instead of the color separation processing by the above described (B-1-2). This is the reason why the importance of each color in the whole picture image cannot be judged simply by the color area and the color difference. More concretely, the color of the background may be determined as a representative color for the reason that the area of the background is wider than the area of the most important object in the picture image in a case of the color separation processing by, for example, the (B-1-2).
Further, there are two methods as described hereinafter even when the picture image is separated through the representative colors by the above described (B-2). Namely, (B-2-1) A plurality of representative colors surrounding the color on the original picture image on the color space so as to approximately express an intermediate color by a dither method through these representative colors. (B-2-2) An interval on the color space between the color on the original picture image and the representative colors so as to convert a color into a representative color nearest in the obtained interval.
Normally the representative color obtained by the above described (B-2-1) dither method can produce a picture image less visually in different feeling as compared with the original picture image than the representative color by the shortest interval of the (B-2-2).
Since the picture image is separated into fine points when the dither method is used, resolution is lowered, and thus causing a defect in that the picture image processing after it is extremely hard to effect.
When such illustration as shown in FIG. 2 is separated in color, an operator selects a proper color from the sensory judgment, first, with the (B-1-3) so as to determine a representative color. An interval in the color space between a color on the original picture image and each representative color is computed by the (B-2-2) so as to convert the color into the representative color which is nearest in the obtained interval. Here partially enlarged views are provided in FIG. 2 through FIG. 4.
When the illustration of the original picture is clearly separated in color by a representative color as shown in FIG. 2, a picture image having a picture cell of an intermediate color is obtained on the boundary of each representative color in the reading of the illustration in the picture image input portion. Therefore, when the picture cell of the intermediate color has been separated in color, the color has to be converted into a representative color for constituting the intermediate color.
In a color space shown in FIG. 6, assume that a position on the color space of a representative color a (white) in FIG. 2 is, for example, A, and similarly, a position on the color space of a representative b (black) is B. In this case, a picture cell on the boundary between the adjacent representative color a (white) and representative color b (black) of a picture image read in the picture image input portion becomes an intermediate color positioned on a straight line connecting a position of a representative color a (white) on the color space with a position of a representative color b (black). Therefore, in the color separation, a color on a segment AB connecting a position on the color space of a representative color a (white) with a position on the color space of a representative color b (black) has to be separated in color into a representative color a (white) or a representative color b (black).
When a representative color c (read) different from the above described representative color a (white) and b (black) exists near a segment AB in the color space, a judgment error in the above described color separation appears on the boundary line of a region (closed space) to be occupied by each representative color when the color separation has been effected by the above described (B-2-2) method. Such picture image as shown in FIG. 3 is not provided as an operator intends to, thus causing such judgment error as illustrated in FIG. 4. Namely, it is found out that the same color as a representative color c (red) appears as noise on the boundary between the representative color a (white) and a representative color (black) in an enlarged view of FIG. 4. This is caused for a reason given hereinabove. Namely, as shown in FIG. 7, a region the representative color c (red) near the position of the segment AB occupies in the color space partially hangs on the segment AB. Therefore, the color of the point to be positioned on the segment AB for passing through the area the representative color c (red) occupies is separated in color into a representative color c (red) though it has to be naturally separated in color into either of the representative color a (white) and a representative color b (black). As a result, as shown in FIG. 4, noises of a representative color c (red) enter the boundary of a representative color a (white) and a representative color b (black) in the color separation picture image.
When block copies for dyeing use are made from the color separation results, an operator has to manually correct such noises one by one with the use of a painting function of a picture image processing apparatus, with a problem that operation efficiency is extremely bad because of many hours required in the correcting operation.